This invention relates to a synchronizer ring stable in quality having a superior friction characteristic and an improved abrasion resisting property and durability.
A synchronizer ring is conventionally utilized for a synchromesh transmission, for example.
The synchronizer ring acts as a friction ring performing a synchronous sliding motion with a rotating opposite object member such as a taper cone and performing a separating motion from the taper cone of a clutch gear, thus significantly serving as a member for rendering equal peripheral speeds of two gears which are to be engaged with each other.
The synchronizer ring of prior art has a structure in which a ring body having an outer peripheral portion on which a plurality of gear teeth, which are engaged with another rotating member, are formed with equally spaced relationship in the circumferential direction. The ring body is further provided with an inner peripheral portion contacting an opposite object such as the taper cone. A plurality of annular grooves are formed to the inner peripheral portion in its circumferential direction for imparting friction force, and at least one groove across the annular grooves may be formed thereto as occasion demands for escaping lube oil. In one type of such synchronizer ring, a key groove to which a synchronizer key is fitted is formed to the outer peripheral portion of the ring body. The synchronizer ring is generally made of brass (Cu-Zn alloy).
For the synchronizer ring of the structure described above, it is required to have an inner peripheral portion contacting another rotating member having an excellent friction characteristic and abrasion resisting property in addition to high mechanical strength and accuracy. Particularly, in the use for speed change gears or gear mechanisms for automobiles, it has been required for the synchronizer ring to have further improved friction characteristic and abrasion resisting property in accordance with recent requirement of a transmission mechanism of an automobile with high grade and performance as well as its improved maneuverability.
In accordance with such recent requirement, various studies have been made for providing a synchronizer ring having an inner peripheral portion having further improved friction characteristic and abrasion resisting property in comparison with the conventional synchronizer ring made of brass (Cu-Zn alloy).
For example, there is provided a synchronizer ring having an inner peripheral portion on which is formed, by a thermal spraying method, a layer formed of a material composed of metal, ceramic and oxide uniformly mixed with and fused to each other. Furthermore, there is also known a method of manufacturing a friction ring having an inner peripheral portion on which is formed by a flame jetting method a friction lining composed of a sintered powder material including metal powder component of 80 weight % and non metal powder material of 20 weight %.
However, the conventional synchronizer rings described above or manufactured by the method described above have not yet met desired friction characteristics and abrasion resisting properties. Furthermore, the conventional synchronizer rings suffer from inadequate strength due to insufficient diffusion of the respective metal components having instable qualities due to unevenness of materials of flame-coated film. Moreover, incompletely fused particles or scattering rebounding particles in the flame form on the surface layer of the flame-coated film, and the adhesion of theses particles onto the surface layer makes the surface of the film coarse. Over time, the friction characteristic of the ring changes and abrasion of parts of a transmission system of an automobile, for example, results from particles dropped down from the film surface. These also provide significant problems. In the conventional art, grinding working or cutting working is performed to the flame-coated film surface for the purpose of reducing the surface coarseness or roughness of the flame-coated film, but such workings are expensive and not economical.